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RE: Streaming scrambled movies

At 2:41 PM +0100 11/9/00, Moreillon Guy wrote:
> -----Original Message----- 
 From: Kevin Marks [mailto:email@hidden]
 Sent: Wednesday, November 08, 2000 11:32 PM
 To: Moreillon Guy; DSS Dev List (E-mail)
 Subject: Re: Streaming scrambled movies


 At 4:10 PM +0100 11/8/00, Moreillon Guy wrote:
 >   The way I've been going so far is to use the sample code for the
 >packetizer and reassembler and add my scrambling code: the packetizer
 >scrambles the video stream as it packetizes during the
 hinting process and
 >the reassembler does the opposite during the playing
 process. This is OK
 >except for a few problems:
 >   + the original video stream is not scrambled in the
 quicktime movie file,
 >the scrambled version is in fact stored in the hint track,
 so the movie can
 >be seen directly on the server using a regular client. I
 have to write my
 >own app to hint the movie and somehow erase or nullify the
 original video
 >track.


if you hint into a file without flattening, the media tracks' media will stay in another file. don't ship that around...

> No-one should be able to see these files on your server if its just
running QTSS. 

Sure, but the movie would be scrambled at location X, transfered to
location Y and streamed without further transformation from there.
There is a security hole between X and Y (and even at Y, no computer
system is secure). We could secure the transfer between X and Y, but
this adds handling. In any case we've now managed to remove the
original movie track and keep only the hinted movie track which is
played without a hitch by the server, so this works fine.


also do-able.

> > + this only works for the YUV2 video encoding since it is 
 the only format
 >for which I have a packetizer/reassembler source code

 You need to generalise your packetisation/reassembly code, to be more
 like the QT packetizer (which will pack any data type). It works by
 just chopping up the media data into packets, and sending a
 SampleDescription every now and then.


I had in mind to keep the specialized packetization algorithms of each
media type so as not to lose on the quality of the broadcast. That is
the whole idea of having specialized packetizers and reassemblers
isn't it? If I packetize/reassemble a Sorenson video stream using the
base packetizer/reassembler, wouldn't I lose on quality in case of
packet loss for example? Or would that be negligeable?

layered packetization/reassembly would seem to be indicated, though I think it is basically uncharted waters...

your packetizer would identify itself as a payload type which claims (a) scrambling and (b) nonetheless identifies the underlying packetizer type (somehow) 'x-scrmabled-sorenson'. it works by calling the sorenson packetizer and then scrambling what it wants to put in a packet. likewise at the other end, it de-scrambles, and then calls the sorenson re-assembler. this is all very glib, as I said, it's uncharted waters...

--
David Singer
Apple Computer/QuickTime

References: 
 >RE: Streaming scrambled movies (From: Moreillon Guy <email@hidden>)



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